Math, asked by amit414132, 4 months ago

cosa=4cos^3a/3-3cosa/3

Answers

Answered by shomekeyaroy79

2

$\small\bf \colorbox{green}{Verified Answer}$

L.H.S = cos3A

= cos(2A+A)

= cos2A.cosA – sin2A.sinA

= (2cos2A - 1)cosA – 2sinA cosA sinA

= 2cos3A – cosA – 2cosA(1-cos2A)

= 2cos3A – cosA – 2cosA + 2cos3A

= 4cos3A – 3cosA

= R.H.S.

Hence Verified

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